GFCIs, such as ground fault circuit interrupters (“GFCIs”), have been widely used by consumers since 1970s. Nowadays, due to household safety concerns, there are needs for GFCIs with extra safety features. According to new UL standards under 934A which are going to be in effective starting in June 2006, a GFCI will be required not only to have reverse wiring protection, but also to be able to provide a user with indications to alert the user when the GFCI has reached the end of its service life and is no longer capable of providing ground fault protection. That is because for most of the GFCIs currently available on the market, when their service life ends, resetting by pressing the reset button is still possible, which gives the users a false sense of security that they are still under proper protection of the GFCI, while in fact the GFCIs' capability of sensing a ground fault and cutting off the electricity due to a ground fault has been compromised. Thus, when a ground fault occurs, the GFCI is unable to provide any protection, which can result in fatal electric shocks.
In the invention to be presented in the following sections, a newly-designed GFCI which is capable of performing an end of life test is provided. The GFCI of the present invention allows the user to detect whether the service life of the device has ended by simply pressing the reset button, if the GFCI can be reset, the GFCI shows continuing capability of detecting a ground fault. If the GFCI cannot be reset, it means that the end of the service life of the GFCI has been reached, and the user should consider replacing the GFCI.